CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Income Statement [Abstract]
Revenue	$ 95,713	$ 73,450	$ 185,868	$ 139,071
Cost of revenue	27,602	20,636	55,461	37,789
Gross profit	68,111	52,814	130,407	101,282
Operating expenses:
Research and development	28,265	26,453	55,172	49,587
Sales and marketing	60,186	58,460	119,658	114,955
General and administrative	17,579	17,675	32,088	33,147
Total operating expenses	106,030	102,588	206,918	197,689
Loss from operations	(37,919)	(49,774)	(76,511)	(96,407)
Interest expense, net	(189)	(229)	(365)	(743)
Other income (expense), net	190	(31)	631	(108)
Loss before provision for income taxes	(37,918)	(50,034)	(76,245)	(97,258)
Provision for income taxes	184	141	432	200
Net loss	$ (38,102)	$ (50,175)	$ (76,677)	$ (97,458)
Net loss per common share, basic and diluted	$ (0.30)	$ (0.42)	$ (0.61)	$ (0.81)
Weighted-average shares used to compute net loss per share, basic and diluted	126,776	120,399	125,864	119,987